BACKGROUND:Fetal pulse oximetry (FPO) may contribute to the evaluation of fetal well-being during labour. OBJECTIVES:To compare the effectiveness and safety of FPO with conventional surveillance techniques, using the results of randomised controlled trials. SEARCH STRATEGY:We searched the Cochrane Pregnancy and Childbirth Group trials register (31 July 2004) and conducted a systematic literature search of MEDLINE (1994 to July 2004), EMBASE (1994 to July 2004) and Current Contents (1994 to July 2004). SELECTION CRITERIA:All published and unpublished randomised controlled trials (RCTs) that compared maternal and fetal/neonatal/infant outcomes when FPO was used in labour, with or without concurrent use of conventional fetal surveillance, compared with using cardiotocography (CTG) alone. DATA COLLECTION AND ANALYSIS:Two independent reviewers performed data extraction. Analyses were performed on an intention-to-treat basis. We sought additional information from the investigators of the one reported trial. MAIN RESULTS:One published RCT (comparing FPO and CTG with CTG alone) was included; and two ongoing RCTs were identified. The single included RCT reported on 1010 cases. Unpublished pilot data were available for some outcomes to give a total of 1190 cases. There was no difference in the overall caesarean section rate between the two groups (relative risk (RR) 1.12, 95% confidence interval (CI) 0.91 to 1.37). There were less caesarean sections for nonreassuring fetal status in the FPO plus CTG group compared with the CTG only group (RR 0.45, 95% CI 0.28 to 0.72). The only reported neonatal seizure occurred in the CTG only group (RR 0.29 95% CI 0.01 to 7.08). Use of FPO with CTG decreased operative delivery (caesarean section, forceps, vacuum) for nonreassuring fetal status (RR 0.71, 95% CI 0.55 to 0.93) compared with CTG alone. No differences were seen for overall operative deliveries, endometritis, intrapartum or postpartum haemorrhage, uterine rupture, low Apgar scores, umbilical arterial pH or base excess, admission to the neonatal intensive care unit or fetal/neonatal death. REVIEWERS' CONCLUSIONS:The one published RCT reported that FPO decreased the caesarean section rate and operative delivery rates for nonreassuring fetal status, without adversely affecting maternal or fetal/neonatal outcomes. However, no difference was seen in the overall caesarean section (CS) or operative delivery rates because more CS were performed for dystocia in the FPO group. Further RCTs may address dystocia in labours monitored with FPO, maternal satisfaction with fetal monitoring and labour, long-term neurodevelopmental outcome of infants who exhibited nonreassuring fetal status in labour and costs of FPO.